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Ritualistic cannibalism in the Palaeolithic

Zigzag marks on a roughly 15,000-year-old human limb bone may be the result of ritualistic cannibalism in ancient Britain.

Marks on bones found in Gough’s Cave in southwest England have previously shown that humans who lived there practised cannibalism for nutritional purposes. A team led by Silvia Bello at the Natural History Museum in London examined a human arm bone excavated from the cave in 1987. The team found evidence that humans had eaten meat from the bone: it bore incisions, human-tooth marks and damage from being pounded with a stone.

However, the radius also bore unusual zigzag marks, which are unlikely to have been created to extract flesh, the authors say. Similar patterns appear on animal bones from other European sites dated to the same period.

This type of intentional engraving has not been seen before on human bones, and suggests a previously unrecognized cannibalistic funerary practice in the Palaeolithic period.

The writing of a letter A, as documented by a high-speed camera that created 4 images over the course of 12 trillionths of a second. Each colour represents an image seen at a separate wavelength of light and each column represents a particular elapsed time. Credit: Y. Lu et al./Phys. Rev. Lett.

A new ultra-fast camera can generate a film of dozens of frames at trillions of frames per second.

High-speed cameras capture frames on light sensors composed of semiconductors. Such cameras typically save each frame of a sequence on a separate area of the sensor. But inherent limits on the sensor’s size can limit the length of a film to just a few shots.

Feng Chen of Xi’an Jiaotong University in Shaanxi, China, Lidai Wang at the City University of Hong Kong and their colleagues instead expose each frame on separate but overlapping areas of the camera sensor. Each successive frame is imprinted with a random tag before it reaches the sensor. These tags allow the image captured by the sensor to be teased apart into distinct frames.

With this technique, the camera could generate a sequence of up to 60 shots at a rate of almost 4 trillion frames per second. This allowed the team to film a light pulse as it travelled through a material.

The imaging system captures a light pulse (in a slowed video) as it passes through a material, exits the material (at the dashed yellow line) and bounces off a mirror (solid yellow line) back into the material.Credit: Y. Lu et al./Phys. Rev. Lett.

The approach could be used to watch high-speed processes — such as the interaction between light and biological tissue in laser surgery — unfold over time.

An oddball galaxy thought to be almost devoid of dark matter seems to have a surprisingly normal population of stars — hinting at a dramatic past.

Dark matter is the enigmatic ‘stuff’ that is thought to make up most of the matter in the Universe, but cannot be detected directly. Researchers think that galaxies are surrounded by dark-matter haloes much greater in mass than the galaxies’ stars. But the faint galaxy NGC 1052-DF2 is an outlier that seems to have little or no dark matter.

A team led by Jérémy Fensch at the European Southern Observatory in Garching, Germany, performed a chemical analysis of DF2’s stars. This revealed that their fraction of relatively heavy elements is similar to that of other galaxies with a similar total mass of stars. This is surprising, because DF2’s lack of dark matter — which exerts a gravitational pull — should make it easier for heavier elements to escape the galaxy.

The finding supports the theory that DF2’s gas, from which its stars formed, originated in a much larger host galaxy with a typical dark matter halo, and was expelled in a collision with another galaxy.

Shards of rock from deep below Mongolia are a window into Earth’s primordial composition.

Earth’s inner heat continuously melts and changes the chemistry of the planet’s crust, and this makes it difficult for scientists to find samples of Earth’s early chemistry. Richard Carlson at the Carnegie Institution for Science in Washington DC and Dmitri Ionov at the University of Montpellier in France scoured Mongolia’s Tariat region and found rocks studded with unusual-looking fragments known as xenoliths.

Chemical analysis of 97 xenoliths shows that they were born beneath the Mongolian crust. The xenoliths are similar in composition to material that, when melted, produces the lava that erupts from seafloor features called mid-ocean ridges. Together these ridges form Earth’s biggest volcanic chain.

This similarity suggests that the Mongolian rocks are a remarkably pristine sample of the large portion of Earth’s interior that melts to feed the mid-ocean ridges, the authors say. The motion of plates of Earth’s crust likely shoved the xenolith source beneath Mongolia hundreds of millions of years ago.

Veromessor pergandei harvester ants, which thrive in colonies tens of thousands strong in the southwestern United States, usually walk a single route each day to collect seeds. Christina Kwapich and Bert Hölldobler at Arizona State University in Tempe monitored the ants’ response when one of their own became ensnared in a spider web.

If the entangled ant released a chemical alarm signal, its companions rescued it, carried it back to the nest and cleaned the silk from its body. Ants also tugged on the web itself until they had destroyed it. In laboratory tests, ants needed between 30 minutes and 2 hours to demolish a single web.

The authors say that although one ant represents only a fraction of the colony, rescue attempts might promote the colony’s long-term survival. This is probably in part because the loss of multiple foragers to webs every day could drastically reduce the number of seeds harvested per year.

The elusive genes that make pathogens drug resistant can be easily detected at last,﻿ thanks to a test based on the CRISPR–Cas9 gene-editing tool.

Medical laboratories use DNA sequencing to detect some pathogens in samples from patients. But it is difficult to spot genes that confer resistance to antimicrobial compounds — such as those that make certain bacteria penicillin resistant — because of their low abundance.

To address this problem, Emily Crawford at the Chan Zuckerberg Biohub in San Francisco, California, and her colleagues developed a method called FLASH (finding low abundance sequences by hybridization). FLASH harnesses a set of RNA molecules to direct the Cas9 enzyme to antimicrobial-resistance genes. Cas9 then cuts the genes’ DNA into fragments that are copied many times before being sequenced.

The authors used the technique to detect antimicrobial-resistance genes in samples from four patients with lower-respiratory tract infections such as pneumonia. They were also able to detect such genes in samples from five people infected with the malaria parasite Plasmodium falciparum.

Tiger sharks are not picky eaters, even as babies. Youngsters of the striped sea predator snack on many species of bird, including some that live primarily on land.

Tiger sharks (Galeocerdo cuvier) are notorious for their ability to eat just about anything, from sea turtles to rubber tyres. Marcus Drymon at Mississippi State University in Biloxi and his colleagues analysed the stomach contents of more than 100 tiger sharks caught off the coast of Mississippi and Alabama at various times of year. The authors found remains of land birds, such as swallows and wrens, in about 40% of the animals — nearly half of which were baby sharks.

How sharks come by land birds is not clear. Tiger sharks’ consumption of land birds occurred mainly during the birds’ migration season, and the researchers suspect that the sharks are snacking on migrating birds that fall into the ocean as a result of storms or fatigue.

This scavenging of land birds may offer young sharks a way to stay well fed until they learn effective hunting strategies, the scientists say.

Personal cooling could be one step closer to reality, thanks to the advent of a flexible cooling device that can be incorporated into clothing.

Thermoelectric systems use semiconductors to pump heat from one side of a device to the other, creating a cool zone and a hot zone. Such systems can provide compact, easily adjustable cooling, but getting them to efficiently dissipate heat has proved challenging.

Renkun Chen, Sheng Xu and their colleagues at the University of California, San Diego, addressed this problem by embedding multiple pillars of a semiconducting material between two stretchy polymer sheets. One sheet served as the hot zone, the other as the cool zone. This design conferred flexibility and insulated the hot and cold sides from each other, allowing the hot layer to dissipate its heat into the air.

The team added a flexible battery pack to the design, creating a patch that can cool skin temperature by more than 10ºC. The use of such devices could reduce the demand for energy to power central air conditioning by 20% in typical buildings, and enhance a wearer’s comfort outdoors, the authors say.

An atomic-force microscope forms images of single molecules and their internal bonds by scanning the molecules with a probe and measuring the repulsive force experienced by the probe’s tip. But bulky molecules that protrude towards the tip alter the force readings, which has an effect similar to throwing the image out of focus.

Daniel Ebeling and his colleagues at Justus Liebig University Giessen, Germany, operated the microscope in a mode that allows an electric current to flow from the tip to the sample. The amount of current corresponds to the tip’s distance from the sample. In the researchers’ protocol, the current is held constant; as a result, the tip’s height changes as it follows a molecule’s contours. This keeps the image of the bonds in focus while simultaneously acquiring data about the molecule’s 3D shape.

Test images of a structurally complex molecule — a triphenylene radical — showed that this technique could keep more of the structure in focus than conventional methods can.

Scientists have charted how the antibodies of a person infected with Ebola virus evolve over time — and the findings suggest that survivors remain protected from the disease for at least three years after recovery.

Infection with Ebola virus triggers immune cells to produce antibodies, which work to fight off the pathogen. Rafi Ahmed at Emory University in Atlanta, Georgia, and his colleagues assessed antibodies in four people who were treated for Ebola at Emory’s hospital in 2014, during an outbreak of the disease in West Africa.

The team found that one set of antibodies surged acutely after infection. Over the next three years, those antibodies diminished in number in all four patients, whereas other antibody subsets rose. Pockets of virus hiding in the eyes and testicles, and viral fragments in lymph nodes, might have triggered production of the later Ebola-fighting antibodies — but they did not cause the disease to recur.

In the future, researchers might be able to﻿ determine whether an Ebola vaccine offers protection by analysing whether it elicits the same antibodies that survivors of the disease developed within six months of an infection.

Harried humans around the world are embracing cheap, ultra-processed foods such as white bread, bacon and hash browns. But the first randomized controlled trial on the health effects of these foods shows that people offered such a diet ingest more calories — and pack on more weight — than they do when presented with more wholesome meals.

To determine how processed foods affect health, Kevin Hall at the National Institute of Diabetes and Digestive and Kidney Diseases in Bethesda, Maryland, and his colleagues fed study participants ultra-processed foods for two weeks. The same participants also spent two weeks eating unprocessed foods, such as fish and fresh vegetables. Both types of meal had the same number of calories, and the same levels of nutrients such as sugar and fat. Participants chose how much to eat.

When offered ultra-processed foods, people ate more quickly and took in an average of 500 more calories per day than when they were offered unprocessed foods. Participants gained roughly 1 kilogram during the trial’s junk-food phase and lost roughly the same amount during the whole-foods phase.

A water droplet falling onto a cool, solid surface creates a series of distinctive halos around its point of impact.

If﻿ a water droplet strikes a surface colder than 0ºC, it can instantly form ice; if the surface is hotter than water’s boiling point, the drop quickly evaporates. To study what happens when the surface is cool, Chun Yang at Nanyang Technological University in Singapore and his colleagues filmed drops of room-temperature water as they struck a surface colder than the dew point — at which condensation occurs — but above water’s freezing point.

The researchers found that vapour evaporating from the droplets condenses on the surrounding surface, helping to form a series of three bands. The edge of the first band marks the extent of the droplet’s expansion on impact. At the instant of impact, water vapour departing the flattened droplet condenses on the surface around it, forming a second band. After the drop contracts and stabilizes, it cools, and vapour wafts outwards, forming a third, outer band.

This behaviour could apply to other processes in which condensation plays a part in heat transfer, the authors write.

Most snails boast a shell that spirals out from the centre in a clockwise direction. But a few ‘lefty’ snails have shells that coil the opposite way, and now scientists know why.

Masanori Abe and Reiko Kuroda, now at Chubu University in Kasugai, Japan, used the CRISPR–Cas9 gene-editing technique in the pond snail Lymnaea stagnalis to knock out a gene called Lsdia1. This encodes a protein that helps to govern a cell’s internal framework.

The team found that snails missing this gene had offspring with the rare anticlockwise shells, suggesting that Lsdia1 is key to determining the creatures’ ‘handedness’. These snails passed on the mutated gene and shell type to subsequent generations; those with functioning copies of the gene had shells that coiled the normal way. The gene influenced the pattern of cell division from the stage at which snail embryos divided from one cell into two.

Research on genes such as Lsdia1 could shed light on a rare human condition called situs inversus, in which the positions of the organs in the body are reversed, the authors say.

Some lemurs are active during the day and sleep at night, like adult humans. Others are active night and day, like human teenagers, and sleep in irregular bursts. David Samson at the University of Toronto in Mississauga, Canada, and his colleagues wanted to know whether lemurs that sleep mostly at night — keeping what is known as a ‘diurnal’ schedule — would be more affected by sleep loss than their more flexible ‘cathemeral’ cousins.

In the first protocol, the team woke some lemurs every 15 minutes over the course of 4 hours by playing recordings of noisy events such as storms and falling food dishes. Other lemurs were left in peace. In a second session, some lemurs were subjected to the noises every five minutes for ten hours. The researchers then tested the primates’ recall and other skills.

Long-term memory suffered in all of the lemurs after nights of terrible sleep, supporting the hypothesis that primates consolidate memories while snoozing. The strictly diurnal lemurs in the genus Propithecus saw the steepest decline in their foraging efficiency, hinting that the cathemeral lemurs — such as the ring-tailed lemur (Lemur catta) — are better able to handle sleep disruption.

Lead from the Roman era pollutes ice buried deep in an Alpine glacier, providing some of the oldest evidence that mining and smelting during the period spread environmental contaminants across Europe.

A team led by Suzanne Preunkert at the University of Grenoble–Alps in France measured lead and antimony levels in an ice core taken from the Alps’ highest mountain, Mont Blanc, which straddles the French–Italian border. The oldest ice in the core dates to about 5,000 years ago.

Lead levels in the core peak twice in antiquity, once in about the second century bc, when the Romans were expanding their territory, and then again in around ad 120, when the empire was flourishing. Levels of the metal were at least 10 times background levels, suggesting that the mining and smelting of lead spread the contaminant across much of Europe. The Romans used lead for pipes, among other items.

Levels of antimony, an element that is often found in lead ore, increased at about the same time as lead concentrations did — suggesting that early Europeans were breathing in a mix of heavy metals.

Key cellular receptors can change their shapes, which might allow them to expand the variety of messages they send to cells.

G-protein-coupled receptors (GPCRs) are protein complexes on cell surfaces, where they pick up chemical and protein signals. After receiving a signal, the receptor releases a messenger called a G protein into the cell. G proteins then direct the cell to make a molecule, for instance, or to carry out a metabolic process.

The human genome encodes more than 800 GPCRs, but only a few dozen G proteins. This﻿ has led researchers to wonder how a receptor translates an incoming signal into a specific message conveyed by a particular G protein.

Xiangyu Liu at Tsinghua University in Beijing, Brian Kobilka at Stanford University in California and their colleagues crystallized the beta-adrenergic GPCR, which binds adrenaline molecules outside of the cell. The team found that, after binding adrenaline, the receptor can shift its shape into one of two different forms. Each of these forms holds the G protein in a different position.

The researchers suspect that there are other forms of the receptor to ensure that it activates the correct G protein.

A giant vortex that forms in the waters off east Africa each year has been tracked in unprecedented detail. This ‘Great Whirl’ might play an important part in the start of India’s southwest monsoon, which drenches the subcontinent in rain but can be difficult to predict.

The Great Whirl typically appears off the Somali coast around May — usually a few weeks before the monsoon kicks in — and lasts until December. Its currents prevent relatively fresh water flowing along the coast from penetrating the Arabian Sea.

Bryce Melzer with Perspecta at the Stennis Space Center, Mississippi, and his colleagues developed an algorithm to track the Great Whirl by monitoring its effect on sea-surface height, which satellites can measure. Piracy off Somalia’s coast makes research trips to the region almost impossible.

The authors studied 23 years of satellite observations and found that the vortex lasted an average of 198 days per year, about a month longer than previous observations had shown. The vortex also covered a bigger area than thought: roughly 275,000 square kilometres, an area greater than that of the United Kingdom.

Learning more about the whirl could help researchers to understand the factors that feed into the monsoon.

A panda that vanished from Asia thousands of years ago survives in the genome of its modern relatives.

The giant panda (Ailuropoda melanoleuca) once thrived as far north as Beijing and as far south as Vietnam, but today the bear lives in only six mountain ranges in central China. To study the effects on the species of its shrinking territory, Gui-Lian Sheng at the China University of Geosciences in Wuhan, Axel Barlow at the University of Potsdam in Germany and their colleagues sequenced nuclear DNA from an approximately 5,000-year-old panda bone found in Yunnan Province, China, which lies well south of the animal’s current habitat.

Analysis indicated that the ancient bone came from a member of a now-vanished group of giant pandas. But DNA analysis also suggested that animals from this extinct lineage interbred with the ancestors of modern pandas millennia ago. The findings imply that giant pandas were more genetically diverse before their range shrank in size.

Healthy human lungs are home to a family of 19 newfound viruses — which are present at higher levels in the lungs of critically ill people.

Earth is swarming with viruses, and so far scientists have documented only a fraction of them. But advances in DNA-sequencing technology are allowing researchers to characterize more of these microbes.

Frederic Bushman, Ronald Collman and their colleagues at the University of Pennsylvania in Philadelphia sequenced genetic material in fluid collected from the lungs of human donors and identified two viruses that have circular genomes. The team then screened thousands of previously collected samples — including both human tissue and other materials, such as soil — for similar genetic sequences.

The screen picked up the two new viruses, as well as 17 related viruses. The researchers dubbed the viral family Redondoviridae, after the Spanish word for round.

The team found redondoviruses along the human respiratory tract in both healthy people and patients in a hospital intensive-care unit. Some people with gum disease also had elevated levels of redondoviruses, but the viruses are unlikely to be the cause of the gum inflammation, the authors state.

The culprit behind a mysterious layer of volcanic ash that blanketed the central Mediterranean 29,000 years ago has finally been found. The ash came from Campi Flegrei, a volcano that is among the most fearsome in Europe.

Campi Flegrei lies near the city of Naples in Italy. Some 40,000 years ago, it unleashed the biggest eruption known to have occurred in Europe over the past 200,000 years. Now, a team led by Paul Albert at the University of Oxford, UK, has fingered it for a major eruption nearly 30,000 years ago that flung ash across an area of more than 150,000 square kilometres, including swathes of Italy and Greece. The scientists dated the ash precisely using the radioactive decay of argon-40, and analysed the chemistry of glass fragments to trace the ash to Campi Flegrei.

The work shows that Campi Flegrei has erupted more frequently than scientists had estimated, and that officials may need to revise their ideas about how often it lets loose big blasts. Campi Flegrei last blew — in a much smaller eruption — in ad 1538.

A new technique could improve the performance of a class of light sources that is revolutionizing materials science.

X-ray free-electron lasers (XFELs) produce brilliant X-ray pulses as short as a few quadrillionths of a second. These brief bursts help to capture fast-moving molecular interactions within a sampled material.

The pulses are made by passing a beam of electrons through a magnet array. This coaxes the electrons into emitting radiation. In one technique, an ultraviolet ‘seed’ laser is trained on the electron beam travelling through a short array of magnets, and a separate array helps to amplify the electrons’ output of radiation at the desired, X-ray frequency. But this amplification process also amplifies imperfections in the electron beam.

Primož Rebernik Ribič and Enrico Allaria of Elettra Synchrotron Trieste in Italy and their colleagues demonstrated an alternative technique that uses two sets of seed lasers. This compresses electrons that emit radiation at one particular X-ray frequency into a tight bunch, creating a powerful pulse of X-rays that are more uniform in frequency than those generated by conventional XFELs.